簡(jiǎn)單使用Mybatis見筆者的上一篇文章：mybatis入門
這篇文章中，筆者將要介紹SpringBoot+Mybatis進(jìn)行簡(jiǎn)單的查詢
使用的是maven建項(xiàng)目受裹，數(shù)據(jù)庫使用的Mysql：
添加SpringBoot相關(guān)依賴：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
添加Mybatis相關(guān)依賴：
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
添加Mysql 相關(guān)依賴：
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>6.0.6</version>
</dependency>
添加Mybatis-SpringBoot 依賴：
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
spring-boot 所做的事情是：
在jdbc上進(jìn)行了一層包裝
當(dāng)程序開始運(yùn)行時(shí)候轮纫，它會(huì)做如下幾件事情：
- 獲取mybatis_config.xml文件洲拇，并通過它，獲得所有的mapper文件路徑
- 掃描所有的類：
獲取其中的@Service @Controller @Component標(biāo)識(shí)的類绅项，自動(dòng)生成一個(gè)相應(yīng)的bean紊册。
獲取其中的@Mapper 標(biāo)識(shí)的接口類，找到其對(duì)應(yīng)的mapper文件快耿，自動(dòng)生成一個(gè)相應(yīng)的bean囊陡，mapper 接口類所有的抽象方法在mapper文件中都有相應(yīng)id標(biāo)識(shí)的sql語句
和單獨(dú)使用Mybatis不同在于，不再需要mybatis配置文件了：
配置SpringBoot資源文件
Application.yml
spring:
datasource:
url: jdbc:mysql://localhost:3306/bookSystem
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: XXX
到這里掀亥，我們有幾種方法
第一種：映射的簡(jiǎn)單形式（不需要配置映射文件）
第二種：配置映射文件撞反，并且建立Mapper接口類
第三種：配置映射文件，不建立Mapper接口類搪花，自己封裝一個(gè)類
第一種：
package demo.mappers;
import demo.domain.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
@Mapper
public interface UserMapper {
@Select("select * from User where userId = #{id}")
User queryById(@Param("id") Integer id);
}
第二種和第三種都需要UserMapper.xml:
一定需要注意的是遏片，資源mapper文件的路徑一定要和mapper抽象類的路徑形式完全相同嘹害，名稱完全相同，不然吮便，程序無法找到相應(yīng)的映射文件
UserMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="demo.mappers.UserMapper">
<select id="queryById" resultType="demo.domain.User">
SELECT * FROM User WHERE userId = #{id}
</select>
</mapper>
這里的namespace是這個(gè)mapper文件所對(duì)應(yīng)的mapper類的路徑
"queryById" 對(duì)應(yīng)了mapper類中的抽象方法
第二種：
package demo.mappers;
import demo.domain.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
@Mapper
public interface UserMapper {
User queryById(@Param("id") Integer id);
}
第三種：
建立一個(gè)類笔呀，比如叫：UserDao.java
package demo.dao;
import demo.domain.User;
import org.apache.ibatis.session.SqlSession;
import org.springframework.stereotype.Component;
@Component
public class UserDao {
private final SqlSession sqlSession;
public UserDao(SqlSession sqlSession){
this.sqlSession = sqlSession;
}
public User selectUserById(int id){
return this.sqlSession.selectOne("queryById", 1);
}
}
第一二種運(yùn)行：
package demo;
import demo.dao.UserDao;
import demo.mappers.UserMapper;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
@SpringBootApplication
public class Application implements CommandLineRunner{
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
private final UserMapper userMapper;
public Application(UserMapper userMapper){
this.userMapper = userMapper;
}
@Override
@SuppressWarnings("squid:S106")
public void run(String... args) throws Exception {
System.out.println(this.userMapper.queryById(1));
}
}
第三種運(yùn)行：
package demo;
import demo.dao.UserDao;
import demo.mappers.UserMapper;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
@SpringBootApplication
public class Application implements CommandLineRunner{
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
private final UserDao userDao;
public Application(UserDao userDao){
this.userDao = userDao;
}
@Override
@SuppressWarnings("squid:S106")
public void run(String... args) throws Exception {
System.out.println(this.userDao.selectUserById(1));
}
}
運(yùn)行結(jié)果相同
以上是簡(jiǎn)單使用，如果想要做的更加完整
需要一個(gè)service:
package db.java.service;
import db.java.domain.User;
import db.java.mappers.UserMapper;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
@Resource
UserMapper userMapper;
@Override
public User queryById(Integer userId) {
return userMapper.queryById(userId);
}
@Override
public List<User> queryByName(String userName) {
return null;
}
@Override
public int add(User user) {
return 0;
}
@Override
public int update(User user) {
return 0;
}
@Override
public int deleteById(Integer userId) {
return 0;
}
}
簡(jiǎn)單起見线衫，只處理了queryById()方法
需要一個(gè)controller
package admin_api.java.web;
import db.java.domain.User;
import db.java.service.UserServiceImpl;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/admin/user") //整個(gè)類是用于處理/admin/user/..的
public class AdminUserController{
private final Log logger = LogFactory.getLog(AdminUserController.class);
@Autowired
UserServiceImpl userService;
@RequestMapping(value = "/query", method = RequestMethod.GET)
public User query(Integer id){
return userService.queryById(id);
}
}
Application:
@SpringBootApplication
public class Application{
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
運(yùn)行
postman中發(fā)出get請(qǐng)求凿可，localhost:8080/admin/user/query?id=1
得到數(shù)據(jù)庫中查詢結(jié)果：
{
"userId": 1,
"nickName": "Alice",
"passWord": "234",
"email": "111@qq.com",
"phoneNum": "112334",
"gender": "female",
"creditScore": 10
}
